Objective:To evaluate the value of dual-energy CT (DECT) mixed images CT in predicting hemorrhagic transformation (HT) after endovascular therapy (EVT) of acute ischemic stroke (AIS).Methods:From October 2018 to January 2020, the immediate dual-energy CT images of intracranial high attenuation (HA) regions in patients with AIS after endovascular treatment in Wuhan No.1 Hospital were retrospectively analyzed. According to the diagnostic criteria of CT or diffusion weighted image in 72 hours of follow-up, they were classified into HT group and non-HT group. The CT value of mixed images, contrast media, and virtual non-enhancement (VNC) and iodine concentration in the highest attenuation areas were measured. Intragroup correlation coefficient was used to evaluate the consistency among the readers; Mann-Whitney U test was used to compare the difference between the two groups of quantitative parameters; Spearman correlation analysis was uesd for evaluating correlation between mixed images CT value and contrast media CT value, VNC CT value, and iodine concentration. The receiver operating characteristic curve was used to analyze the quantitative parameters to predict the diagnostic efficacy of HT. Results:A total of 154 cases were enrolled, with 65 cases in the HT group and 89 cases in the non-HT group. The intraclass correlation coefficient of CT values of mixed images was 0.861 ( P<0.05). Comparing the non-HT group and the HT group,the CT value of mixed images [59.40(54.84, 63.05) HU vs 100.10(79.90, 122.40) HU, Z=-10.87, P<0.001],contrast agent CT value [24.90(20.75, 30.05) HU vs 66.60(47.10, 84.15) HU, Z=-10.85, P<0.001] and iodine concentration [1.10(1.00, 1.30) mg/ml vs 2.90(2.05, 3.65) mg/ml, Z=-10.85, P<0.001] both increased in the HT group, but there was no significant difference in VNC CT values between the two groups [33.60(31.80, 35.70) HU vs 34.30(30.90, 38.00) HU, Z=-0.50, P=0.62]. There was a highly significant correlation between the CT value of mixed images and iodine concentration ( r=0.99, P<0.01). Using CT value>72.60 HU as the diagnostic cutoff value for predicting HT, the sensitivity and specificity were 89.23% and 95.51%, respectively. Conclusions:The CT value of DECT mixed images after EVT can be used to predict HT within 72 hours. When DECT was not available, conventional CT scan′s intracranial HA density over 72.60 HU can be selected as the cutoff value for predicting HT.